1. Field of the Invention
The present invention relates to an information processing apparatus and a method therefor, and in particular to an information processing apparatus and a method therefor employing a 3D model (computer aided geometry model in 3D) generated by using 3D-CAD.
2. Related Background Art
Conventionally, a CAD apparatus (especially, a 3D-CAD apparatus) is employed to design objects (hereinafter simply referred to as parts) having a three-dimensional shape, such as parts for goods or products. Further, based on this design, metal molds for manufacturing parts are generated.
Before using the design information prepared by the CAD apparatus, attribution information, such as dimensions, dimensional tolerances, geometric tolerances, annotations and symbols, are entered for a 3D model (computer aided geometry model in 3D).
In order to enter this attribution-information for the 3D model, planes, ridge lines, center lines and vertexes of the 3D model are selected. For example, attribution information shown in FIG. 29 is entered for a 3D model shown in FIG. 27 (the front view, the plan view and the side view of this 3D. model are shown in FIG. 28). The attribution information includes:    (A) distances (lengths, widths and thicknesses), angles, hole diameters, radii, chamfering dimensions, and dimensional tolerances accompanied by dimensions;    (B) geometric tolerances and dimensional tolerances to be added to planes and ridge lines, without dimensions being entered;    (C) annotations to be transmitted or instructed for machining or manufacturing parts, units and products, and symbols that are determined in advance as a premise for representing, for example, surface roughness.
For adding attribution information to a 3D model, roughly two methods, as follow, are employed.    (1) Method for adding dimensions, dimensional tolerances, geometric tolerances, annotations and symbols            Dimension lines and projection lines are required for the entry of dimensions and dimensional tolerances.        Leader lines are required for the entry of geometric tolerances, annotations and symbols.            (2) Method for adding dimensional tolerances, geometric tolerances, annotations and symbols without dimensions being provided.            Dimension lines and projection lines are not required.        Leader lines are required for the entry of dimensional tolerances, geometric tolerances, annotations and symbols.        
For a downstream process, such as a metal mold manufacturing process, attribution information is confirmed by referring to a CAD model or a 2D drawing (drawing in 2 dimention), and molding products and metal mold parts are inspected.
For the metal mold manufacturing process, the inspection of molding products is performed after the metal mold design, the NC programming, the metal mold manufacture and the molding steps have been completed.
For the inspection of a molding project, a manual measuring instrument or an automatic measuring instrument, such as a CMM, a microscope or a micrometer, is employed based on such design information as the designated dimensional tolerances for a drawing or a model.
A three-dimensional measuring instrument measures (for each plan) a molded product in each of several directions, such as the obverse, the reverse and the right and left of the product. When a 2D drawing is employed, a double measurement is performed by adding marks to the measured dimension, or carefully without missing a measurement.
When a molded product is inspected in the conventional manner, the following problems have arisen.    (1) The measurements must be conducted while taking into account which measurement instrument should be employed for each dimension, and the same dimension must be referred to many times to determine whether it has already been measured, or whether it should be measured by employing the measurement instrument being used at the pertinent step. Thus, an extended period of time is required to complete the measurements.    (2) The measurements must be conducted in order by using each measurement instrument or each plan for a measurement instrument. For example, measurement steps are conducted in the following order: dimension measurements are performed using a CMM (three-dimensional measurement instrument), then, a microscope is used, when there are measurements that not obtained using a CMM, and if all such measurements are not obtained using a microscope, a micrometer is used. The total measurement time, therefore, is extended.    (3) Design information for several tens, or hundreds or more dimensions are provided as attribution information for a drawing or a model. For the measurement of dimensions, required information must be extracted to identify the portion that is to be measured, and for a complicated model, target dimensions must be searched for while the measurements are being made. Therefore, an extended period of time is required.    (4) Since marks representing measurements that have been obtained are added to a drawing while the measurement process is in progress, omissions, clerical errors and oversights tend to occur. And frequently, at the end of the measurement process, an examination reveals portions that were missed or for which measurements were not obtained, and measurements made for the dimensions of these portions must be repeated using the individual measurement instruments. Therefore, time for backtracking is required.    (5) The measurement values and the portions measured using measurement instruments are transferred to paper and are compared with the dimensions. Therefore, time is required to perform this comparison of the measurement results.
Furthermore, identifiers are added so that sizes can be compared with measurement results. Therefore, measurement values are generally recorded with the identifiers, so that measurement results can be compared with dimensions to which identifiers on a drawing are attached.
In Japanese Patent Application Laid-Open No. 5-282388 a dimension inspection apparatus adds an identifier to a CAD drawing and prints a measurement examination sheet, or outputs data to a measurement instrument.
According to this method, the system automatically adds identifiers and displays data in order to reduce the labor effort required and to eliminate errors. The contents of the identifiers to be added need not be designated in advance.
In addition, in Japanese Patent Application Laid-Open No. 08-082575 a method and an apparatus for generating and displaying an evaluation table automates the collection of measurement results, so as to improve the efficiency of the measurement process.
Further, described in Japanese Patent Application Laid-Open No. 08-190575 are “an apparatus and a method for teaching an inspection”, and described in Japanese Patent Application Laid-Open No. 2000-235594 are “a CAD system and a method for inspecting a measured dimension value”, while the measurement instrument is limited to a CMM and an identifier for a dimension is added to CMM path data, so that a measured value is output with the identifier to the output file of the three-dimensional measurement instrument and the measurement results can be read by the CAD system and compared with the dimensions. Furthermore, a CAD system available on the market also handles a method for adding an identifier to a dimension and outputting CMM path data, and for reading the measurement results and comparing them with the dimensions.
When the measurement results are to be compared with the dimensions, however, conventionally, the following problems and requests have arisen.    (6) The conventional technique limits the measurement instrument that is used to an automated measurement instrument, such as a CMM, and does not support the use for a measurement operation of a manual measurement instrument, such as a micrometer.    (7) Even an automated measurement instrument, such as a CMM, may not easily prepare a measurement program on a CAD screen (off-line teaching), and the conventional technique does not support the generation (on-line teaching) of a measurement program using a CMM.    (8) The capability of an operation using a manual measurement instrument and the off-line teaching using an automated measurement instrument is not taken into account for the conventional automatic identifier addition system. Thus, an improved function for transmitting information to an operator (a function for the visibility of an identifier, etc.) is required.    (9) In the inspection process, a large number of steps are required for manual on-line teaching and for manual measurement. Therefore, for both aspects of the cost and the delivery deadline, a demand exists for the improvement of the operating efficiency and for a reduction in the number of steps.    (10) Measurements must be conducted while taking into account which measurement instrument should be employed for each dimension, and the same dimension must be referred to many times so as to determine whether it has been already measured, or whether it should be measured by employing the measurement instrument used for the pertinent step. Thus, an extended period of time is required for measurements.    (11) Measurements must be conducted in order by using each measurement instrument or in accordance with a plan that provides for the use of each measurement instrument. For example, measurement steps are performed in the following order: dimension measurements are normally performed using a CMM (three-dimensional measurement instrument), then, a microscope is used when there are measurements that are not obtained using a CMM, and if all such measurements are not obtained using a microscope, a micrometer is used. The total measurement time, therefore, is extended.    (12) Conventionally, a 2D drawing is employed to transmit design/manufacturing information, and a great number of steps is required for the generation of the 2D drawing. To eliminate this problem, it is anticipated that when a “paper drawing-less” (hereinafter referred to as drawing-less) process is implemented whereby design information is transmitted by adding design/manufacturing information, such as dimension tolerances, to a 3D model, the number of steps required for the transmission of data can be considerably reduced.    (13) A method for performing measurements while referring to the dimensional tolerances added to a 2D drawing is set up for the inspection step, and a system for efficiently measuring dimensions while referring to attribution information added to a 3D model is required to implement the “drawing-less” process and to reduce the number of data transmission steps and the cost.    (14) Design information for several tens or hundreds or more dimensions are provided as attribution information for a drawing or a model. Then, for the measurement of the dimensions, required information must be extracted to identify portions to be measured, and for a complicated model, target dimensions must be searched for while the processing for the measurements is conducted. An extended period of time is therefore required.    (15) Since marks representing the measurements that have been completed are added to a drawing while the measurement process is being performed, omissions, clerical errors and oversights tend to occur. And frequently, after the measurement process has been completed, a drawing is examined and a portion is found that was missed and for which measurements were not obtained, and for this portion the dimensions must again be measured using individual measurement instruments. Time is therefore required to counter this setback.
At an inspection step, measurement points representing a portion to be measured are determined for the addition of attribution information, such as dimensional tolerances, and a measurement program is generated that provides for the use of a manual measurement instrument for the measurements.
Using a pen, marks are added to portions on a drawing printed on paper as measurement points that correspond to locations that are to be measured, or measurement points are added to a CAD model using a CAD apparatus. Further, a measurement program is prepared by referring to the information for the measurement points added to the CAD model.
Then, at the NC programming step, offset values equivalent to cut margins are added as attribution information to the CAD model and an NC program is prepared.
When the CAD model is later changed by altering its design, generally it is exchanged for another model during the downstream process, and additional information, such as measurement points currently carried by the CAD model or offset values equivalent to the cut margin, is added to the CAD model after the change.
Usually, when a plurality of operators handle the same data, the following three methods are employed.
A. Exclusive Control
A change right is designated for data, and only an operator having this right may change that data. When another operator is to correct data for which a change right exists, the current holder of the change right must terminate any alteration operation, stabilize the data being processed, and release the right change to the other. Then, the other operator, to whom the change right has been transferred, may operate on the stored data. The change right is owned by only one person at a time.
B. Synchronization Across a Network
When a computer transmits alteration information as operating change procedures to other computers to which it is connected via a network, the altered content is reflected in the data originally held by the receiving computers.
C. Manual Re-input
A portion containing changes is evaluated and manually employed so it is reflected in the CAD model for which the added information is provided, or the added information is used for the re-entry of data in the model being updated.
When data has been shared in the above described manner, the following problems and demands have arisen.    (16) For exclusive control, it is difficult for parallel operations to be simultaneously performed, even though consistency of data by using common data can be maintained.    (17) Synchronization across a network must be controlled by the operator of a terminal connected to the network, and temporarily proceeding with an independent operation is difficult.    (18) Although additional information can be re-entered manually and independently, the labor for re-entry and entry of omissions may be required.    (19) When data is altered, it is also difficult to identify the portion that has been altered.